First of all, you need to downlaod TOPMOD program. Then start to play around with the tools and available shapes in Topmod program. Once you are happy with your piece, you need to save it as an obj file.
Next step is open your rhino, import your obj file and scale you model using offsetmesh command. scale the model as you desired. for my model is used 50x50x50 for jewelery size and 100x100x100 for architectural size. after you are happy with you model and your scale, save your file as an stl. file. then open the file in magic program and use the command fix manually. remember to thick all of those ‘fix’ list. Once your model get fixed, its ready to be send to http://www.shapeways.com to be modeled.